A primary goal of aircraft design today is the safety of the passengers and crew, particularly in the event of an emergency landing. The importance of this goal can be seen throughout the design of the aircraft including its seats. Some illustrative aircraft seat designs are shown in U.S. Pat. Nos. 4,440,441; 3,531,154; 3,460,791 and 3,354,990 the contents of which are incorporated by reference. Industry standards have been adopted to maintain consistent seat performance to enhance occupant safety during the event of an emergency landing.
One standard adopted by the aircraft industry to regulate seat design is Aerospace Standard SAE AS8049 entitled Performance Standard for Seats in Civil Rotorcraft and Transport Airplanes. This standard encompasses a variety of design considerations. The aircraft seat must be capable of withstanding a simulated emergency landing that produces a predetermined impact pulse curve. This impact pulse curve depicts the forces transmitted to the seat during the simulated emergency landing. The seat must dissipate some of the energy and forces that would otherwise be transmitted to the occupant. SAE AS8049 specifies that the occupant should not experience spine compression of greater than 1500 pounds or a shoulder harness load of greater than 1750 pounds during the simulated emergency landing test. The standard also contains other requirements, such as maximum permanent deformation, hazardous projections, fire protection and workmanship that must be incorporated into the seat design.
A main problem in aircraft seat design is meeting the impact pulse requirements, such as the maximum force and spine compression requirements, set forth in Aerospace Standard SAE AS8049. This problem is aggravated by the fact that the soft cushions may increase the level of forces experienced by the occupant in some situations.
Another significant problem in aircraft seat design is that the seat must withstand the simulated floor warping criteria of Aerospace Standard SAE AS8049. This standard requires the seat to withstand significant aircraft floor warping that may arise from the forces associated with an emergency landing. The seat must be able to withstand floor warping equated to a 10.degree. roll, 10.degree. pitch of the floor tracks. A 10.degree. yaw of the aircraft is also included during the test.
A further problem in aircraft seat design is meeting the deflection requirements set forth in Aerospace Standard SAE AS8049. The legs of the seat should not crush more than a prescribed amount in order to prevent harm to the occupants of the aircraft. Longitudinal, lateral and rotational deflection must all be kept within the tolerances set forth in Aerospace Standard SAE AS8049.
A still further problem in aircraft seat design is that conventional aircraft come in variety of sizes and shapes, and for a variety of functions. Aircraft range from single engine sport planes, to large airliners or supersonic fighter aircraft, to helicopters. The seat design should be capable of being installed in as many aircraft as possible.
A still further problem in aircraft seat design is producing a seat that is both economical to manufacture and install in conventional aircraft. Typically, the more substantial the changes to an existing aircraft seat the more expensive the new design will be to manufacture. Significant changes to the existing seat design may also prevent the seat from fitting into an existing aircraft floor plan, thus rendering the design unusable.
The present invention is provided to solve these and other problems.